To strict pacifists, no war is ever justified, even in self-defense. To many others, war is justified in direct self-defense, that is, in direct response to an attack. Examples of wars justified in response to an attack would be American entry into World War II after the bombing of Pearl Harbor, or the war against al-Qaeda and its Taliban allies in Afghanstan after the terrorist attack now known simply as "9/11."
Other claimed justifications for war are less clear, but not necessarily to be rejected out of hand. A case could well be made that the US would have been justified to attack the Japanese task force as it steamed toward Pearl Harbor, without waiting for bombs to fall. In quite a different situation, a case could be made that NATO was justified in going to war to prevent "ethnic cleansing" in Kosovo in 1999, even though NATO members were not directly threatened, to prevent genocide and put an end to the series of aggressive actions by the Serbian regime of Slobodan Milosovic.
Was the war against Iraq justified even under these broad standards? One way to test this proposition is to examine the validity or truthfulness of the arguments that the Bush Administration gave for going to war. Few doubt that the Saddam Hussein regime was odious; in the 1980s and early 1990s it committed both atrocities against its own people and aggression against two neighbors. However, the Bush Administration's assertions of justification for war were not based on Saddam's general odiousness or his past behavior. Rather, the justifications given were assertions of links between Saddam and al-Qaeda, and an urgent threat arising from Iraq's possession of so-called weapons of mass destruction (WMD).
Both of these claims have been decisively refuted. The claimed link to al-Qaeda was always questionable, given that the Baathist regime in Iraq and al-Quaeda represented very different and rival positions in Middle Eastern ideology an...